Spatiotemporal Dynamics of Functional Traits and Quantitative Characteristics of Phragmites australis at Different Microtopographic Levels in the Upper Reaches of the Yellow River Beach Wetland

Based on the previous field survey, undisturbed natural community vegetation areas were selected and surface elevations were measured using RTK altimeters. The China Geodetic Coordinate System (GCS) 2000 was selected as the reference sea-level coordinate system. The elevation was measured at 10-m intervals in the study area. Fifteen P. australis community sample plots were set up according to different microtopographies (high, medium, and low terrain) for investigation. Moreover, seven fixed sample squares (1 m × 1 m) were randomly selected in each sample plot, totaling 105 sample squares, and the growth of P. australis in the sample squares was investigated in detail.